铜钼复合添加ZnO-TiO_2微波介质陶瓷的低温烧结及相转变

Sintering and Phase Transition of 0.25CuO-0.75MoO_3 Doped ZnO-TiO_2 Microwave Dielectric Ceramics

研究了添加0.25CuO-0.75MoO3(摩尔比,简记为CM)对ZnO-TiO2(简记为ZT)陶瓷的低温烧结特性、相转变及微波介电性能的影响.CM添加的ZT陶瓷由传统的固相反应方法制备而得,烧结温度限定在900～1050℃范围内.样品的显微形貌、元素成分、物相构成及微波介电性能分别由FE-SEM、EDS、XRD及网络分析仪进行表征或测量.EDS及XRD分析显示,Cu2+和Mo6+均进入了ZT陶瓷的主晶相的晶格,并导致ZnTiO3分解温度的降低,同时,也降低了在Zn2TiO4和金红石之间形成固溶体(Zn2Ti3O8)的起始温度.实验结果表明,CM的添加可有效地促进ZT陶瓷的低温致密化烧结.添加4wt%CM且在975℃烧结4h后的ZT陶瓷的密度可达理论值的94%,其微波介电性能为品质因素Qf=12150GHz,介电常数εr=28.6,谐振频率温度系数τf=+17.8×10-6/℃.

The effects of 0.25CuO-0.75MoO3 （in mole ratio, abbreviated to CM） addition on the sintering behavior, phase transition and microwave dielectric properties of ZnO-TiO2 （ZT） ceramics were investigated. CM-doped ZT ceramics were prepared by conventional solid-state reaction method and sintered at temperatures ranging from 900℃ to 1050℃. The micrographs, elemental composition, phase structures and microwave dielectric properties of the samples prepared were characterized or measured by field-emission scanning electron microscopy （FE-SEM） equipped with an energy dispersive spectroscopy （EDS）, X-ray diffraction （XRD） and a network analyzer, respectively. It is demonstrated that both Cu^2＋ and Mo^6＋ are introduced into the lattice of the main phase which lower the decomposition temperature of ZnTiO3 and the onset temperature at which Zn2TiO4 and rutile could form solid solution （Zn2Ti3O8）. Meanwhile, it is confirmed that, the doping of CM can effectively enhance the densification of ZT ceramics at relatively low sintering temperatures. The ZT ceramic sample with 4wt% CM addition sintered at 975℃ for 4h reaches a density value of 94% theoretical density, and exhibited microwave dielectric properties as follows： dielectric constant εr=28.6, quality factor Qf=12150GHz and temperature coefficient of resonant frequency τf=＋17.8×10^-6/℃.